Method For Bleeding Air From Hydraulic Circuit - Komatsu PC490LC Installation And Instruction Manual

MAINTENANCE
The gas springs are located at the engine hood (2 places on
right and left sides).
In the following cases, ask your Komatsu distributor for inspection, repair, and replacement.
• The engine hood is heavy to open.
• Oil or gas is leaking from the gas spring.

METHOD FOR BLEEDING AIR FROM HYDRAULIC CIRCUIT

When starting the engine, see "METHOD FOR STARTING ENGINE (3-173)". If necessary, see the paragraphs
for starting the engine, and moving/steering/stopping the machine in OPERATION section.
METHOD FOR BLEEDING AIR FROM PUMP
NOTICE
If the drain hose is installed first, oil will spurt out from bleeder (1) hole.
If the pump is operated without filling the pump case with hydraulic oil, abnormal heat will be generated
and this may cause a premature damage to the pump.
1.
Loosen air bleeders (1) (2 places) and check that oil oozes out from the air bleeder.
2.
If the oil does not ooze out, remove drain hose (2) from the
hydraulic pump case and fill the pump case completely
with hydraulic oil through drain port.
Oil will come out when the drain hose is removed, so se-
cure the hose fitting at a position higher than the level of
the oil in the hydraulic tank.
3.
After completing the air bleed operation, tighten air bleeder
(1) and install the drain hose.
METHOD FOR STARTING ENGINE
Start the engine according to "METHOD FOR STARTING ENGINE (3-173)" and run it at low idle for 10 minutes,
and then start the following work.
METHOD FOR BLEEDING AIR FROM CYLINDER
NOTICE
If the engine runs at high speed immediately after startup or a cylinder is operated to its stroke end, air
taken inside the cylinder may cause damage to the piston packing.
1.
Start the engine.
2.
Turn the fuel control dial to Low idle (MIN) position.
3.
Move each cylinder to approximately 100 mm before the stroke end, and repeat the operation 4 to 5 times.
Take care not to move the cylinder to the stroke end.
4.
Turn the fuel control dial to High idle (MAX) position.
5.
Move each cylinder to approximately 100 mm before the stroke end, and repeat the operation 4 to 5 times.
Take care not to move the cylinder to the stroke end.
6.
Turn the fuel control dial to Low idle (MIN) position.
MAINTENANCE PROCEDURE
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